Anamorphic downconversion can be very sharp but kinda jaggy and shimmery on vertical camera pans (Toshiba) or a bit soft but with no jaggies or shimmers (Sony). I've had both Sony and Tosh players in the past, as well as a Panasonic which fell between Sony and Tosh in this respect.
My JVC, when I used it with my previous Hitachi 4/3 analog rptv, was similar to the Panasonic--some jaggies and shimmers but not as bad as the Toshiba, and a sharper picture than the Sony.